<!DOCTYPE html>
This iframe should have a border.<br>

<iframe frameborder="1" src="about:blank"></iframe>

<br>

This iframe should not.<br>

<iframe frameborder="0" src="about:blank"></iframe>
<br>

This iframe should have a border.
<br>

<iframe frameborder="0" style="border:2px inset" src="about:blank"></iframe>
